1. Technical Field
The present disclosure relates to advantageous methods and apparatus for spinal stabilization. More particularly, the present disclosure relates to devices, systems and methods for providing dynamic stabilization to the spine via the use of an intermediate multi-level connector for dynamic attachment of elongated members spanning one or more spinal levels at multi-level orientations.
2. Background Art
Back pain is most frequently associated with degenerative or traumatic changes in the lumbar vertebrae and/or disks. The vast majority of the 30 million U.S. patients who report back pain each year resolve their pain with conservative treatment or, simply, rest and exercise. However, approximately 15 percent, or 4.5 million, low back pain sufferers fail conservative therapy and are left with debilitating pain. Of these, some 500,000 opt for surgery.
In addition to alleviating pain, spine surgery seeks to minimize damage to adjacent supportive muscle and skeletal tissues. Spine fusion used to be the only option for patients, and remains the most common surgical procedure. However, the by-products of this surgical procedure and preparation for fusion are damage of the posterior muscles and loss of intervertebral motion which can compromise postoperative function and place abnormal stresses on the adjacent spine levels.
New treatment modalities, collectively called motion preservation devices, are currently being developed to address these limitations. Some promising therapies are in the form of nucleus, disc or facet replacements. Other motion preservation devices provide dynamic internal stabilization of the injured and/or degenerated spine, e.g., the Dynesys stabilization system (Zimmer, Inc.; Warsaw, Ind.) and the Graf Ligament. A major goal of this concept is the stabilization of the spine to prevent pain while preserving near normal spinal function. Dynamic spinal stabilization systems use non-rigid materials to stabilize the affected lumbar region, to alter the load bearing forces and stress patterns in the affected region, and to preserve the anatomy and mobility of the spine by preventing degeneration in adjacent regions.
Dynamic stabilization designs may vary according to spine level, from cervical to thoracic to lumbar to sacral. For posterior systems, screw or hook based systems are widely used and are secured to rods, plates or other forms of stabilization members. The lumbosacral junction can bear the largest loads on the spine and the highest stresses. Further, the S-1 pedicle, made up for five fused vertebrae below the lumbar region, is larger than the lumbar pedicles, having Sacral Ala or “wings”, and presents unique anatomical problems in spinal stabilization methodologies.
With the foregoing in mind, those skilled in the art will understand that a need exists for spinal stabilization devices, systems and methods that preserve spinal motion, that include dynamically attached elongated members for implantation across one or more levels of the spine.